Linkage mechanism for circuit breakers



Feb. 27, 1968 M. LALLEMAND 3,371,178

LINKAGE MECHANISM FOR CIRCUIT BREAKERS Filed March 22, 1966 v 3Sheets-Sheet 1 Feb. 27, 1968 M. LALLEMAND 3,371,178

LINKAGE MECHANISM FOR CIRCUIT BREAKERS Filed March 22, 1966 3Sheets-Sheet 2 Feb. 27, 1968 M. LALLEMAND 3,371,178

LINKAGE MECHANISM FOR CIRCUIT BREAKERS Filed March 22. 1966 5Sheets-Sheet 5 United States Patent ice 3,371,178 LINKAGE MECHANISM FORCIRCUIT BREAKERS Marcel Lallemand, Argenteuil, France, assignor toSociete Anonyme dite: Continentale & Garner, Paris, France, a Frenchcompany Filed Mar. 22, 1966, Ser. No. 536,388 8 Claims. (Cl. 200-153)ABSTRACT OF THE DISCLOSURE A mechanism for a circuit breaker which is ofsmall dimensions, especially in thickness, which gives completeprotection. against overloads and short-circuits. One of two pivotallyconnected links is itself pivoted at a fixed point, the other linkhaving a pin slidably engaged in a pivotally mounted slide, the pinbeing connected to a third link which has a second pin slidably mountedin a fixed slide having an elbow and an operating member is adapted tomove the second pin in the second slide into the elbow portion to lockthe mechanism so that a movable contact connected with the first andsecond links bridges the fixed contacts to close the circuit.

The present invention concerns an operating mechanism for a circuitbreaker or the like.

Circuit breakers are known which comprise an operating and lockingmechanism which, when an operating button is pressed, and in the absenceof a fault, maintains a movable contact element or elements of thecircuit breaker in engagement with fixed contacts and, locks theoperating member in its closed position.

The subject of the present invention is an operating mechanism for acircuit breaker or the like, which has a reduced number of elements andwhich is relatively simple and of a reduced size.

A mechanism in accordance with the invention comprises two links whichare hinged with respect to one another and of which one is pivotallymounted at a fixed point whilst the other carries a pin engaging a slidewhich is itself pivotally mounted at a fixed point, the moveable contactof the apparatus being connected to one of the links, preferably at thepivot common to the two links, with spring means tending to pivot thelinks so that they tend to move away from the fixed contacts, a catch orstop to prevent the slide from pivoting and means for displacing the pinin the slide and to maintain the pin in a locked position in which themoveable contact bridges the fixed contacts, characterized in that themeans for displacing the pin in the slide and maintaining it in itslocked position comprises a third link which is operatively connected tothe pin and to an operating member of the linkage which is hinged on afurther pin sliding in a fixed slide, this second slide comprising aportion which is essentially parallel to the position which the firstslide occupies when it is prevented from pivoting and which is followedby an elbowed portion, the auxiliary pin at the end of the operatingmember engaging with the second slide.

The invention also envisages a circuit breaker or like device providedwith a mechanism of the type defined 3,371,178 Patented Feb. 27, 1968FIGS. 3 and 4 represent the mechanism after release;

FIG. 5 is an exploded perspective view of a circuit breaker;

FIG. 6 is a view in perspective of the support members of the circuitbreaker looking in the direction of the arrow F of FIG. 5.

As represented schematically in FIGS. 1 to 4, the mechanism comprises aslide 1 which is carried by a lever 2 pivotally mounted at a fixed point3. In front of the end of the slide 1 away from the pivot 3 there is, inthe absence of an overload, a retractable stop 4 which is pivotallymounted at 5.

A pin 6 engages the slide 1, on which are pivoted two links 7 and 8. Thelink 7 carries a pin 9 at its end op-. posite the pin 6, which engages afixed slide 10, the latter having an elbow 10a. The link 8 is connectedby pivot 11 to a link 12 which is pivoted at one end at a fixed point13. A spiral pring 14, tends to rotate this link 12 in the directionindicated by the arrow 15. The angle formed by the two links 7 and 8must be less than and preferably less than 15; in fact if this angle isgreater than 90 the link 7 would be more or less diametrically oppositethe one shown, which would substantially increase the height of themechanism.

On the pivot 11 is hinged a link 16 which carries a movable contact 17adapted to bridge the fixed contacts 18a and 18b; finally, an operativemember 19, acted upon by a return spring'41, permits the displacement ofthe pin 9 in the slide 10. This pin is normally returned to the upperpart of the slide 10 by the action of the spring 41 on the lever 19.

The mechanism functions in the following manner. At rest (FIG. 1), thespring 14 tends to displace the pivot 11 and the link 8 upwardly, themechanism being assumed to be vertical and to occupy the position shownin the drawings; the moveable contact 17 is thus remote from the fixedcontacts 18a and 18b. The movement of the pin 6 is limited by the link7, the pin 9 of which rests against the base of the slide 11). Themovement of the pin 11 is limited by the contact 17 which rests againstthe casing of the apparatus 56a and 56b. The arrangement of the parts inthe rest position is such that a space 1 exists between the upper partof the slide 1 and the stop the lever 12 against the action of thespring 14; link 16 applies the moveable contact 17 to the fixed contacts18a and 18b.

At the end of the movement, the pin 9 moves into the elbow part 16a ofthe slide under the effect of the couple, with respect to the pin 6, ofthe resistance of the forces P and T, P being the force exerted on theoperating member 19 and T the force exerted on the pin 9 by link 7. Themechanism is now in its locked position (FIG. 2). A spring connectingmember 21 is provided between the moveable contact 17 and the pivot 11to ensure a balanced pressure on the fixed contacts 18a and 181). Toprovide an improved locking effect a spring can be added to displace pin9 downwardly towards the base of the elbow part 10a of the slide 10; inthe drawings this is shown as a leaf spring 22 one end of which isfixed, the other bearing on an extension 23 of the link 7. A stop 24alimits the displacement of their free end.

Under the elfect of the spring 14-, the pin 6 exerts on the slide 1 aforce along the direction of the link 8. Consequently, when the stop 4is tripped by an overload, the slide 1 pivots in the direction of thearrow at the same time, the pin 6 moves upwardly in the slide. Thismovement frees the pivot 11 which moves up under the action of a spring14 bringing the moveable contact 17 with it; at the same time the link 7moves round its pivot 9 until its extension 23 meets the stop 24b (FIG.3). From this position, the link 7 pivots around the point of contact ofits extension 23 with fulcrum 2411, which disengages the pin 9 from theelbowed part 10a of the slide 10 and frees the operating member 19 (FIG.4).

From the drawings it can be seen that the positions of the link 7 withits extension 23 and of the leaf spring 22 is such that this spring hasno action on the pin 9, as this pin is disengaged from the elbowed part10a. The operating 19 moves upward under the action of its return spring41 and brings the slide 1 back into its initial position (FIG. 1). Themechanism is ready to be reoperated when the overload has disappeared.

If the operating member is depressed when the stop 4 is not in itsnormal position, displacement of the pin 9 only effects a pivotingmotion of the slide 1, the pivot 11 and the contact 17 remainingimmobile. The circuit therefore cannot be closed. FIGS. 5 and 6 show acircuit breaker provided with a mechanism of the type described above.

The elements of this mechanism are mounted in two support members and 26connected one to the other by bolts, the assembly being enclosed in acasing formed from two halves 27 and 28. The fixed parts of themechanism, in particular the pivots 3, 5 and 13, the leaf spring 22 andthe stop 24a and fulcrum 24b, are carried by the members 25 and 26;extensions 3' and 5' for the pivots 3 and 5 can also be seen on themember 26. The operating member 19 passes between the two elements 25and 26 and carries, at its narrow end, a slot 29 for the pin 26; theoperating member pivots on the pin 9. This member is connected to apress button 30 which is in contact with a further press button 31, thecross section of the two buttons being circular. The two buttons areslidingly mounted in a fixing 32 which is externally threaded andcarries, at its narrow end, feet 33 engaging with the shelves 27 and 28;these carry internal studs 34 which engage in holes 35 provided in thefeet. Fins 19a of the operating member 19 are horizontally bent andspaced in the housing of the button 30 so that, when the button 30 isdepressed the interlocking of the mechanism is effected as indicatedpreviously. The upper face of the button 31 is under projection of thebutton 30. The retractable button is extended above its pivot 5 by afork 4a which is positioned with its back to the foot 36a of adisengaging bar 36; this latter is moveably mounted in the member 26,parallel to the direction of a displacement of the buttons 30 and 31,and comprises a horizontal flap 36b disposed in the track of the button31. The depression of this latter button has the effect of displacingthe bar 36 downwardly, which, in pivoting the abutment 4a, frees theslide 1 and ensures its disengagement. Springs 37 and 38 tend to drawback the bar 36 into its upper position, and the abutment 36 into theposition in which it is immobile on the slide 1.

The button 31 comprises an extension 39 which passes through an opening40 of the member 19 which is mounted in a recess of the button 30. Thisextension has a boss 39a at its lower end which serves to guide a returnspring 41 bearing against the horizontal upper faces of the members 25and 26. This spring maintains the button 31 in engagement with thebutton 30; it also tends to displace the member 19 with its pin 9upwardly, this movement being limited by engagement of the pin 9 withthe upper edge of the slide 10.

In one form, the circuit breaker comprises two entry terminals 4212-4212and two outlets 43a and 43b. The terminals 42a and 4312 form a bridgebetween the fixed contacts 18a and 18b. The two terminals 42b and 43bare connected to one another by a conductor 44, a winding 45 providedwith a core 46, a holding strip 47 and a conductor 48; the completecircuit is totally isolated electrically from the principal contactscontrolled by the mechanism. In another form this control circuit is inseries with the main contacts; in this case, the terminals 42a and 421)are omitted and the contact 18a is directly connected to the winding 45by the connection 44. The strip 47 is fixed to the end of a bimetalstrip 49 which serves to compensate for the ambient temperature and ismounted in a reverse sense to the strip 47; this strip 49 is itselffixed to the support member 26 by means of a stirrup 56, the legs ofwhich can be spaced apart to any required degree by the regulating screw51. The free end of the strip 47 is fixed to a plate 52 which can slidein the member 26. The interior edge of this plate is in the proximity ofa projection 4b integral with the fork 4a. The strip 47 is mounted sothat deformation under the effect of a rise in temperature of the outeredge of the plate 52 and of the projection 4b, are drawn together; itcan be seen that, if the rise of temperature is sufficient, that is tosay if the current through the circuit breaker exceeds a given value,plate 52 pushes back the projection 41; which pivots the stop 4 andopens the circuit breaker. The tripping current can be set by movementof the screw 51.

A magnetic plate 53 is mounted on the pivot 54 provided on the outerface of the member 26 and on the inner face of the half shell 28. Thisplate comprises a foot 53a which engages in a slot 55 provided in thedisengaging bar 36. When this bar is in its upper position, in theabsence of an overload, the lower edge of the slot 55 maintains the foot53a in a position in which the free end of the magnetic plate is remotefrom the core 46.

If a short circuit is produced in the circuit controlled by the circuitbreaker, the magnetic field in the winding 45 reaches a value such thatthe core 46 attracts the plate 53 against the action of the spring 37which upwardly displaces the bar of the disconnector 36 and ensures theopening of the circuit breaker.

It can be seen from the preceding description that the circuit breaker,which is of small dimensions especially thickness, gives completeprotection against short-circuits.

I claim:

1. An operating mechanism for a circuit breaker having a movable contactand fixed contacts comprising, a first link pivotally mounted to a fixedpoint, a second link pivotally connected to said first link, one of saidlinks being operatively connected with said moveable contact, apivotably mounted first slide, a first pin positioned on said secondlink and slidably engaged in said first slide, spring means urging saidlinks to pivot away from said fixed contacts, a retractable stop adaptedto prevent said slide from pivoting, a third link connected to saidfirst pin and having a second pin, an operating member connected withsaid second pin, a second slide having a portion which is essentiallyparallel with respect to said first slide when said first slide isprevented from pivoting by said stop and an elbow portion, said secondpin being slidably engaged in said second slide.

2. The mechanism defined in claim 1 wherein said third link is hinged onsaid second pin.

3. The mechanism defined in claim 1, wherein said operating member ispivotally mounted on said second pin.

4. The mechanism defined in claim 1 further comprising a second springurging said second pin into said elbow portion.

5. The mechanism defined in claim 1 further comprising a fulcrum and anextension on said third link which pivots about said fulcrum when saidretractable stop is retracted to disengage said second pin from saidelbow.

6. The mechanism defined in claim 4 wherein said extension abuts saidsecond spring as said second pin References Cited slides through saidsecond slide while said retractable UNITED STATES PATENTS stop is in anunretracted position so that said second pin 2 911 494 11/1959 Rigert200153.9 XR

is forced 1nto sa1d elbow but does not abut sa1d extension when saidretractable stop is retracted. 5 312511240 5/1966 Fredenck 20O453-9 XR7. The mechanism defined in claim 6 wherein said FO G PA second andthird links include an angle which is less 1234141 10/1960 France thanninety degrees.

8. The mechanism defined in claim 7 wherein said angle ROBERT SCHAEFER,Primary Examineris less than fifteen degrees. 10 H. BURKS, AssistantExaminer.

